Film-forming and wiping distillation process and apparatus for carrying out the same



A. F. SMITH 3,020,211 FILM-FORMING AND WIPING DISTILLATION PROCESS Feb.6, 1962 AND APPARATUS FOR CARRYING OUT THE SAME 2 Sheets-Sheet 1 FiledNOV. 28, 1958 36 MII!! 62 .IIL

ARTHUR F. SMITH FJ INVENTOR.

6 5 R R R O N E LE R mm mw N m mm MMMI'MAKbI'NLI'TEIVDInE AP EA AD VM HJX O PW E c c O l 2 M 5 nIU. I.

ATTORNEY Feb. 6, 1962 A. F. SMITH 3,020,211

FILM-FORMING AND WIPING DISTILLATION PROCESS AND APPARATUS RoR CARRYINGOUT THE SAME Filed Nov. 28, 1958 2 Sheets-Sheet 2 l 9A` ll INVENTOR.ARTHUR F. SMITH ATTORNEY ttes 3,020,211 FILM-FRMING AND WIPINGDISTILLATIN FRDCESS AND APPARATUS FR CARRYING GUT THE SAME Arthur F.Smith, 1516 Lake Road, Webster, N51. Filed Nov. 28, 1953, Ser. No.776,739 14 Claims. (Cl. 2132-64) Serial No. 571,626, tiled March l5,1956 and now U.S.

Patent No. 2, 955,990, granted October 1l, 1960i.

For eicient fractional distillation, it is customary to maintaincounter-current contact between distilland, that it, the liquid that isbeing distilled, and the vapor that is formed during distillation.Frequently, this is accoi plished in a tower in which vapors are passedupwardly through packing or bubble caps, while liquid is passeddownwardly, and intimate contact is effected between the vapor andliquid at successive levels in the tower.

These expedients are not available, or are not satisfactory, fordistillations at reduced pressure, and particularly for distillationunder high vacuum, because the packing or bubble caps ofrer resistanceto the passage of vapor. Moreover, expedients of this type require thatthe liquid be maintained at distilling temperature for a relatively longperiod of time, and thus subject the liquid to increased thermal hazard.

It has been proposed in the past, for example in the United Statespatent of DYarmett, 2,040,837 and 2,040,- 838, and of Perry et al.,2,539,699, to employ distillation apparatus in which a rotary brushY ismounted coaxially within a cylindrical shell so that the bristles of thebrush engage the shell wall at least initially. The brush is mounted ona hollow, cooled shaft. Vapor is passed upwardly through the shell andis condensed on the bristles of the rotating brush, and is returnedunder centrifugal force to the shell wall, for reheating, andrevaporization. Stills of this type effect reasonably goodfractionation, but have the mechanical disadvantage that if both brushand shell are made of metal, the brush galls on the metal shell and bothwear rapidly. Moreover, if the shell is not formed with a perfectlycylindrical evaporating surface, the engagement of the bristles againstthe evaporating surface is not uniform; and after some bristle wear,parts of the evaporating surface may not be engaged at all, so that hotspots develop which produce burning and charring. When a metal brush isemployed in conjunction with a glass shell, the thermal efficiency ofthe still is quite low, because of the poor conductivity of the glass.

One object of the present invention is to provide fractionaldistillation apparatus of relatively simple construction, that has highthermal etliciency, that offers an extremely low thermal hazard, andthat is free from hot spots, burning, and charring.

A related object of the invention is to provide frac tional distillationapparatus of the falling lm type, in which the liquid in the tilm iscontinuously redistributed over dterent portions of the evaporatingsurface, to maintain a high degree of turbulence and high thermalconductivity.

Another object of the invention is to provide a practical fractionatingstill for high vacuum distillation, that provides a large number oftheoretical plates in a minimum volume.

ECC

Another object of the invention s to provide fractional distillationapparatus that effects intimate and thorough contact betwen vapors andliquid, even at high vacuum, with a minimum space requirement, and withan extremely low throughput time.

A further object of the invention is to provide a more etiicientfractionating process for separating liquids into fractions, andparticularly, a process that is useful for the fractionation of viscousliquids of low thermal conductivity.

In the drawings:

FIG. l is a section of a fractionating still, the fractionatng portionof the still being shown by a section taken on the line 1 1 of FIG. 2,looking in the direction of the arrows, the remainder being an axialsection, the still being particularly adapted for use at reducedpressures, and constructed according to one embodiment of thisinvention;

FIG. 2 is a section taken on the line 2-2 of FIG. l, looking in thedirection of the arrows;

FIG. 2a is a fragmentary section similar to FIG. 2, but showing a modiedconstruction according to another embodiment of the invention;

FIG. 3 is a fragmentary section taken on the line 3-3 of FIG. 2, lookingin the direction of the arrows;

FIG. 4 is aV section similar to the Section of FIG. 2, but showing afractionating partial condenser structure that is constructed accordingto another embodiment of the invention;

FIG. 5 is a schematic diagram illustrating the closed thermal circuitthat'preferably is employed in conjunction with stills constructedaccording to this invention;

FIG. 6 is an axial section taken on the line 6-6 of FIG. 7, looking inthe direction of the arrows, of a fractionating still that is.particularly adapted for operation at high vacuum, constructed accordingto another ernbodirnent of the invention;

FIG. 7 is a section taken substantially on the line 7--7 of FIG. 4,looking in the direction of the arrows; and

FIG. 8 is a view in elevation, taken on the line 8 8 of FIG. 7, lookingin the direction of the arrows.

Referring now in detail to the drawings by numerals of reference, andparticularly to FIGS. 1, 2, and 3, 10 denotes a casing that is adaptedto be supported in an upright position and that has a bottom bulbportion 11 of generally spherical contour. A nipple .12 is secured tothe bulb portion 11 at its lowest point, to permit drainage of liquidfrom the bulb. A valve or stop cock 14 is connected to the nipple 12, topermit this line to be closed off in vacuum tight fashion.

The casing 1t) has a cylindrical portion 15 that is integral with thebulb 11-1 and whose axis is aligned with the center of the bulb. Aninlet tube or arm 16 is secured to the cylindrical portion 15approximately midway between its ends. The tube 1-6 is generallyupwardly directed, and a funnel member 17 is secured, in vacuum tightfashion, to the upper end of the tube 16. The lower end of the funnelmember 17 is formed with a reduced portion 2t) that projects into thetube 16, in radially spaced relation to the wall of the tube. The funnelmember 17 preferably is formed at its upper end with an internal groundfemale surface 21, in which a male member can be inserted in vacuumtight fashion.

The casing 10 is enlarged at the upper end of the cylinder 15, and isilared outwardly, and downwardly, and is then continued upwardly again,to provide a head 26 that is of enlarged diameter relative to thecylinder 15, and that drains into a gutter or alembic 22. A generallydownwardly directed tube 24 is connected to` the gutter 22, to permitliquid that accumulates in the gutter to be drained. The tube Z4 isformed at its outer end with a 3 ground male surface 25, for vacuumtight connection to a receiver (not shown).

The head 26 is formed at its upper end with an outwardly thickened wallportion to provide a flat base 27 on which a cap Eil is mounted. The cap36 is formed with a ring-shaped channel in its lower face, and an -ring31 is seated in the channel and is compressed between the cap 30 and thesurface 27, to provide a vacuum tight seal.

A coil 2S is mounted in the head 26, with its inlet and outlet linespassed `through the wall of the head 26 in vacuum-tight fashion. Thecoil convolutions are disposed closely adjacent the inner surface of thewall of the head 26, to permit condensate to drain into the gutter 22. Anipple 29, of relatively large diameter, is secured to the wall of thehead 26 adjacent its upper end. The nipple 29 is formed at its outer endwith a ground male surface 32, for vacuum-tight connection to a vacuumpump or other evacuating means.

A bearing is mounted centrally in the cap 30, and a hollow shaft 36 isrotatably journaled in the bearing 35, in vacuum tight fashion. Theshaft 36 projects into the casing 10 substantially coaxially with thehead 26 and the cylinder 15. A plug 37 is mounted in the bore of theshaft 36 at its -lower end, to close the lower end of the shaft. lAshort shaft 4G is secured to the lower face of the plug 37 to projectdownwardly, coaxially with the shaft 36, and an irnpeller 41 is securedto the lower end of the shaft 40.

A partial or fractionating condenser 42 is mounted on the shaft 36, torotate upon rotation of the shaft, within the cylindrical portion 15 ofthe casing 16. The axial length of the condenser 42 corresponds roughlyto the axial length of the cylindrical portion 15, and the upper end ofIthe condenser terminates at a level below the gutter 22. The condenser42 comprises three plates 44 that are equiangularly spaced about theshaft 36. Each of these plates is curved in horizontal section, and itscenter portion is engaged in an axially-extending groove in the shaft56, yas shown in FIG. 2. The plates 44 can be secured to the shaft 36 byspot welding, bolts, or other convenient means (not shown). In makingthe assembly comprising the three plates 44 and the shaft 36, the plates44 preferably are irst curved to the desired shape, then are pressedwith the shaft 36 on a mandrel to be sure that the grooves that areformed in the shaft 36 and the curved center portions of the plates 44conform. Three axially extending plates 45 are secured between theconfronting surfaces of adjacent plates 44, at equally radially inwardlyspaced locations from their free ends, to form three generally U-shapedaxially extending channels. plates 46, that are curved insubstantially-the same manner as the plates 44, are secured to theplates 44, in spaced relation thereto, by end pieces 47 that are weldedin vacuum-tight fashion, or otherwise secured, between the adjacentradial ends of the plates 44, 46 respectively. Other strips 49 (FIG. l)are secured in vacuum-tight fashion across the space between the upperand lower adjacent ends of each pair of plates 44, 46, respectively, toprovide three closed chambers 48 between the three pairs of spacedplates 44, 46 respectively. Each chamber 48 is bounded at its sides byone of the plates 44, two of the upright strips 47, the plate 46 that issecured to the two strips 47, and the upper and lower end closure strips49. Apertures Si) are provided, at spaced upper and lower axiallocations along the shaft 36, to provide communica.- tion between thebore of the shaft 36 and the three chambers 48, iat the axially upperand lower ends of the chambers. A pair of rings S1, 52, are secured tothe upper and lower ends yof the plates 44, 46 respectively, to rigiditythese plates. The lower ring 52 provides a stop at the lower end of thethree channels.

A plurality of wiper elements 54 `are mounted one above the other ineach of the three channels. These wiper elements 54 are curved at theirupper ends, as shown in FIG. 1, so that they can slide freely one `onthe other,

Three other 1 for independent outward radial movement under centrifugalforce as the shaft 36 and the condenser 42 are rotated. Each wiperelements 54 is formed with `a plurality of Slots 55 that are milled ormolded in its face, to provide a plurality of lands 56 that engage theinner or evaporating surface of the cylindrical portion 15, uponrotation of the condenser. The slots 55 are formed with parallel Wallsthat are inclined to the horizontal, so that relative to a clockwisedirection of rotation of the condenser 42 relative to FlG. 2, the slotsare inclined downwardly from the leading edge of the wiper 54 to itstrailing edge.

in the modified form of the invention shown in FIG. 2A, the cuter plates46 yare curved at their lower ends, as denoted at 57, so that theaxially-extending spacers 47 are eliminated.

o provide means for rotation of the shaft 36, a pulley wheel 6d issecured to the portion of the shaft 36 that projects upwardly through-the bearing 35.

To permit the circulation of heat exchange fluid to and from thecondenser 42, a rotary coupling 61 is connected to the upper end oftheshaft 36. The coupling 61 is of a standard make, such as, for example,the type described in US. Patent 2,407,745; and it includes a nipple 62that is threaded, in Vacuum tight fashion, into the upper end of theshaft 36, for rotation upon rotation of the shaft. The nipple 62 isrotatably journaled in a housing 64. A tube 67 depends downwardly fromthe housing 64 coaxially within the bore of the shaft 36, and the boreof the tube 67 communicates with the fluid outlet 66 within the housing64, in iiuid tight fashion. The annular space between the tube 67 andthe shaft 36 communicates with the inlet 65, within the housing 64, influid tight fashion. A metal ring 70 is welded or otherwise securedbetween the lower end of the tube 67 and the inner surface of the shaft36, to close the annular lspace to the iiow of heat exchange lluid belowthe upper set of apertures 50.

To heat the casing 10 during distillation, I prefer to employ .anelectrical heating jacket 71 of standard type. However, I may also applyheat directly to the bulb 11 as well as, or instead of, to the wall ofthe cylinder 15.

While the casing 19 can be supported in substantially any convenient,desired manner, I prefer to support it by a modified pipe coupling 72,that engages the upper end of the head 26, around the outwardly iiaredupper portion of the head. The coupling 72 can in turn be supported froma stand or in any other convenient manner. The coupling 72 is secured tothe cap 30 by bolts 74.

To use this apparatus for a batch fractional distillation, a quantity ofthe liquid, that is to be distilled, is introduced into the casing 10through the funnel member 17. The funnel member 17 is then closed invacuum tight fashion. The liquid runs down the inner surface of the wallof the cylinder 15 into the bulb 11. A receiver is connected to thenipple 24 that drains the gutter 22, and the nipple 29 is connected to avacuum pump. The pulley wheel 60 is driven to rotate the shaft 36, andthe impeller 41 agitates the liquid in the bulb 11, throwing some of itup into the cylinder 1S, and constantly exposing fresh surfaces of theliquid so that degassing is facilitated as the casing is evacuated. Heatis applied to the casing through the heating jacket 71 and, initially,by a burner that is played directly on the lower surface of the bulb 11.Air is caused to circulate into the heat exchange uid inlet 65, throughthe annular space between the tube 67 and the shaft 36, through theupper set of apertures 50 and into the three condenser chambers 48, fordownward passage through the condenser chambers to their lower ends,thence back through the apertures 50 at the lower ends of the chambersand into the bore of the shaft 36, -to travel upwardly into the bore ofthe tube 67, thence to be discharged through the outlet 66. Coolingfluid, such as, for example, cold water, is circulated through thecondenser coils 28 in the head 26 of the casing.

Instead of circulating air through the chambers 48,

I can connect the coil 28 to discharge into the inlet 65, to circulatewater through the chambers 48. In this way, both the condenser 42 andthe coil 28 are water cooled, but the coil 28 is always the cooler ofthe two.

When distilling temperature is reached, vapors are given off by theliquid in the bulb 11, and pass upwardly into the cylinder 15. Thevapors condense on the other surface of the cooled plates 46, and thecondensate is caused to tlow, by centrifugal force, on the surface ofthe plates 46 radially outwardly until it ows from the condensingsurfaces back onto lthe inner, evaporating surface of the cylinder l5.

The condensate that flows on to the evaporating surface flows downwardlyover the evaporating surface in a film, under the influence of gravity,and as it flows downwardly, it is heated by heat from the heating jacket7l, and also, by some heat transfer that occurs with the ascendingvapor. As the liquid ows downwardly over the evaporating surface, theliquid is continuously removed from the evaporating surface by thewipers 54 that are thrown outwardly under the infiuence of centrifugalforce as the shaft 36 is rotated, to engage the evaporating surface. Theremoved liquid passes into the slots 55, and is accelerated downwardlyover the evaporating surface and then is discharged back onto theevaporating surface, again to flow downwardly over the evaporatingsurface in a iilm under the influence of gravity. The wiping actionaccelerates the ow of liquid over the evaporating surface, so that theliquid in film form is subjected to an extremely low thermal hazard.Moreover, the action of the wipers Se maintains the liquid in the fiimin a highly turbulent state, so that excellent heat transfer isobtained,

even though the liquid may be viscous and characterizedv by low thermalconductivity.

After repeated vaporization and condensation during its upward travel,some vapor passes from the cylinder into the head 26, and is condensedon the coils of the condenser 28. The condensate falls into the gutter22, and can be collected in a receiver secured to the nipple 24.Distillation is continued until the desired fraction has been collected.To discontinue the distillation, the liquid should be cooled undervacuum, to prevent any charring that might occur upon exposure of theheated liquid to the atmosphere. If desired, several separate fractionscan be collected. The performance of even a small column, having adiameter on the order of three to six inches for the cylindrical portion15, is on the order of several theoretical plates, and sharply definedfractions can be collected easily.

To use the apparatus illustrated in FIG. 1 for con-Y tinuousdistillation, the input liquid is supplied continuously, at a desiredfeed rate, through the funnel shaped member 17, from which it falls downover the evaporating surface of the cylinder f5. For continuousoperation, the impeller 4l. need not be employed, and can be detached.The undistilled residue is withdrawn continuously through the nipple 12and the opened valve 314. Sufficient heat is applied through the heatingjacket 71 to evaporate or distill a fraction of the desired size, thatcondenses on the coil 28. As the liquid is fed into the cylinder 15, itis immediately subjected to the wiping action, that insures optimum heattransfer and minimum thermal hazard. For a continuous operation, bestresults are obtained by controlling still operation according to thesize of the fraction that it is desired to separate.

Stills of this type are particularly desirable for the recovery ofvitamin A from fish oils, and for the recovery of vitamin E from vitaminE concentrates, because unusually high concentrations can be obtained bysingle pass through the still, because of its fractionating ability.This still is also very valuable for the purification of drugs that havea high intrinsic value and low thermal stability, and which often areparticularly difficult or impossible to fractionate and recover by othermeans. Small laboratory models of the still are valuable research toolsfor many purposes. For example, when the product recovery (total)condenser is not operated, and the fractionating condenser is operatedat equilibrium, valuable equilibrium data can be obtained that is usefulfor many purposes.

rhose skilled in the art will readily recognize that many variations inthe structure and arrangement of the still components are possible,within the scope of my invention. For example, as shown in FIG. 4, tosimplify the still structure, I can mount the plates 44' on the shaft 36as before, with wipers 54 mounted in generally U-shaped channels thatare provided between the confronting, radially outer surfaces of theplates 44 and the axiallyextending plates 45. In this simplifiedembodiment of the invention, the heat exchange uid is circulateddownwardly through the annular space between the shaft 36 and the tube67', and is withdrawn through the bore o-f l `the tube 67'; and foroptimum cooling characteristics, I prefer in this embodiment of theinvention to extend the tube 67' concentrically downward within theshaft 36 almost to the bottom of the shaft. The plates 44 are coldestwhere they are secured to the cooled shaft 36', and become progressivelywarmer in a radially outward direction. While this structure isconsiderably simplified as compared with the structure shown in FIG. 2,the condensing action may be less complete.

Particularly for larger stills, l prefer to employ a closed thermalcircuit in which a single heat exchange fluid is circulated and iscaused to heat the distilland to effect Vaporizatio-n, and to effect,while at a cooler temperature, both partial condensation in thefractionating condenser and total or least substantially completecondensation in the final or upper condenser. For this purpose, it isdesirable to employ a heating jacket on the still, thro-ugh which the.heat exchange fluid, in the hot phase of its cycle, can be circulated.

A preferred form of closed thermal circuit is illustrated schematicallyin FIG. 5. A heat exchange fluid, preferably a phase-changing fluid, iscompressed in a vapor compressor, to transfer energy to it to make ithot. The hot heat exchange fluid is passed through a heating jacket toeffect vaporization of the fluid in my fractionating column. As appliedto FIG. 1, for example, the hot heat exchange fluid would be circulatedin a jacket about the cylinder 15, to transfer heat to the liquid in thefilm on the evaporating surface, to cause it to vaporize. In this partof the cycle, the heat exchange fluid loses heat and becomes cooler. Thecooled heat exchange fluid is recovered and passed through an expansionvalve that reduces its pressure rapidly and that causes self-cooling.The coid fluid is then passed successively through the total condenser,then through the partial condenser. In these condensers, the fluidbecomes increasingly warmer. The fluid is withdrawn from the partialcondenser at an elevated temperature and is compressed in the vaporcornpressor, to heat it for another cycle. As applied to the apparatusin FIG. l, the cooled Huid would pass from the expansion valve throughthe coils of the total condenser 28, thence through the inlet to passdownwardly through the annular space between the tube 67 and the wall ofthe shaft 36, to be passed through the apertures 5t? into the condenserchambers 4S for downward passage in these chambers, thence to returnthrough the lower set of apertures 5t) for passage upwardly through thebore of the tube 67, to be discharged through the outlet 66 andcompressed in the vapor compressor.

The horizontal or transverse curvature of the condens ing surfaces canalso be moditied, within the scope of the invention. Referring to FIG.2, it can be seen that as the condenser is rotated, a portion of thecondensate that forms on a given condensing surface, of one curved plate46, is returned to the evaporating surface at the trailing edge of onecolumn of wipers, and the balance, probably slightly more than half, ofthe condensate is returned to the evaporating surface at the leadingedge of the following column of wipers. The condensate that is allreturned to the evaporating surface at the leading edge of the column ofwipers is immediately spread on the evaporating surface by this columnof wipers, so that a high degree of turbulence is maintained and littleor no splashing occurs at this point. At the trailing edge of the samecolumn of wipers, the condensate that is returned to the evaporatingsurface is acted on substantially only by gravity, until it is struck bythe following column of wipers. By modifying the transverse curved shapeof the condensing surfaces somewhat, to provide a teardrop type ofcurvature, l can cause a larger percentage of the condensate to bereturned to the evaporating surface at the leading edge of each columnof wipers. in such a modification, the condensing surface would fallback sharply, that is, radially inwardly, at the trailing edge of eachcolumn of wipers, to reach a maximum depth at a location not farangularly spaced from the trailing edge of that column of wipers, andthen would curve outwardly toward the leading edge of the followingcolumn of wipers, so that a major portion of each condensing surfacewould be sloped toward the leading edge of one of its associated columnsof wipers.

I can use one or more columns of wipers. For mechanical reasons, Iprefer to use two or more columns of wipers in an equiangularly-spacedarrangement, to distribute evenly the load on the bearings. For largestills, for example, six or eight columns of wipers may be employed.

Referring now to the modied embodiment of the invention shown in FGS. 6,75 denotes a generally cupshaped base that is adapted to be supported ona plurality of legs 76. A bearing '77 is secured to project through thelower part of the base 75, and a shaft 73 is journalcd in this bearing77. A pulley wheel '79 is mounted on the lower end of the shaft 78, topermit the shaft 7S to be rotated by a suitable drive belt and motor(not shown). A rotor gli, that is generally shaped like a flower pot, issecured to the upper end of the shaft for rotation within the base 75. Aplurality of electrical heaters 81 are disposed in the space between theconfronting surface of the rotor 30 and the base 75, A generallyU-shaped gutter 82 is mounted adjacent the upper end of the rotor, and asplash ring 84 is seated in the gutter 32, and is formed with agenerally radially inwardly projecting flange that extends over theupper edge of the rotor.

To supply heated feed liquid to the rotor Si?, a heat exchanger 85 ismounted adjacent the base 75, and feed liquid from a pump 86 is forcedthrough coils S7, within the heat exchanger y8S, thence outwardlythrough a pipe S8 that is bent over upon itself, within the still, andthat has a free lower end 90 that is bent laterally, to direct the feedliquid onto the lower surface of the rotor t), in the direction o-frotation of the rotor.

The splash ring S4 is disposed to catch liquid residue as it leaves therotor 80, and to direct it into the gutter 82. To remove the residuefrom the gutter 82, a line 91 is connected from the gutter S2 to a pump92, that forces it through the heat exchanger 85, in which it transferssome of its heat to the input liquid in the coils 87.

A dome 94, that is generally shaped like an inverted cup, is mounted invacuum tight fashion over the base 75. The dome is provided with aninternal jacket 95 through which cooling fluid may be admitted thro-ugha line 98, to cause condensation on the dome, and a ringr 96 is mountedin the dome, beneath the jacket 95, to recover the condensate.

A fractionating condenser 97 is suspended on struts 99 from the dome.This condenser is formed with a lower, generally horizontal disc 11G andan upper, generally horizontal disc 111. A plurality of curved metalmembers 112 are secured between these two discs to provide a pluralityof generally vertically extending condensing surfaces 11d (FIGS. 7 and8) that lare curved7 in horizontal section, so that they are concaverelative to the evaporating surface, which is the inner, generallyconical surface of the rotor St). A plurality of plates 116 are secured,respectively, between the confronting surface of the metal members 112,adjacent their radially outward, free ends, to provide six generallyaxially extending, U-shaped channels. A pipe 117 is secured at its upperend to the dome to communicate with the jacket remote from the coldwater inlet 98, and is extended downwardly and, adjacent its lower end,is connected to a ring-shaped manifold pipe 12d. Six risers 122 (FIG. 6)are disposed in contact with the plates 116 and with the adjacentportions of the confronting surfaces of the members 112. The lowermanifold ring 120 is connected to the lower ends of these risers 122through restricted openings that provide uniform flow of cooling lluidinto the risers. The risers 122 are connected at their upper ends to anupper manifold ring 124i, which in turn is connected to a discharge pipe125. This pipe 125 is connected at its upper end to a centralcompartment 126 of the jacket 95, that is separated from the rest of thejacket by a baille 127. Water is discharged from the compartment 126through a line 13h. Cooling water thus can be caused to circulate fromthe dome jacket 95 through a line 117 into the lower manifold ring 120,up the risers 122 into the upper manifold ring 124, through the line 125into the compartment 126, thence out the discharge line 130, at theupper center part of the dome.

Columns of wipers 131 are mounted in the U-shaped channels of thecondenser 97, and preferably are spring pressed outwardly by springs 132in the channels, for engagement against the surface of the rotor 80under the influence of gravity and under the spring pressure. Eachcolumn of wipers is supported at its lower end on the disc 110. Eachwiper in each column is free to move outwardly, independently of theother wipers in the column, to engage the surface of the rotor 80'.

As shown in PPG. 8, the condensing surfaces 114 have a plurality ofsmall gutters 134 welded or Otherwise secured to their faces, to receivecondensate as it ows downwardly on the condensing surfaces, collect it,and return it, under the inlluence of gravity, to the evaporatingsurface of the rotor. These gutters 134 are inclined, to return thecondensate to the evaporating surface immediately in advance of a columnof wipers 131.

A large manifold 138 is connected in vacuum-tight fashion to the still,for connection to a diffusion pump for evacuation of the still.

To operate a still constructed according to this embodiment of theinvention, the still is evacuated, and current is passed through theelectrical heaters S1 to heat the rotor Si?. The rotor 80' is rotated,and feed is pumped into the still, by the pump 86, through the line 88,to the lower end of the rotor. Centrifugal force causes the liquid tospread rapidly over the rotor surface in a thin film, and to climbupwardly to be discharged from the upper end of the rotor onto thesplash ring 84, for collection in the gutter S2. As the liquid travelsover the inner surface of the rotor 80, it is heated, and at the sametime, is repeatedly removed from the rotor surface by the wipers 131,and reapplied thereto, to produce a kturbulent film. In this embodimentof the invention, the inclination of the slots in the wiper elements canbe moditied to direct the removed liquid downwardly or upwardly, asdesired, to prolong or to shorten the throughput time for the liquid inthe still, as desired. For example7 if it is desired to increase thethroughput time of the still, the wiper slots would 'be inclined todirect the removed liquid downwardly on the rotor. Some of the liquidvaporizes and condenses on the condensing surfaces 114. The condensatefalls downwardly in a thin film over` these surfaces under the iniluenceof gravity, collects in the gutters 134, and is returned to the rotorsurface, where it is reheated and spread in a turbulent lm over therotor surface by the wipers. Vapor that passes upwardly to the dome iscondensed on the cooled inner surface of the dome, and the condensate 9collects in the ring 96, and is recovered as a product fraction.

While the invention has been described in connection with severalspecific embodiments thereof, it will be understood that it is capableof further modification, and that this application is intended to coverany variations, uses, or adaptations of the invention following, ingeneral, the principles of the invention and including such departuresfrom the present disclosure as come within known or customary practicein the art to which the invention pertains and as may be applied to theessential features herein before set forth, and as fall within the scopeof the invention or the limits of the appended claims.

Having thus described my invention, what I claim is:

1. Apparatus for the distillation of liquid comprising a body having achamber that is formed with an internal surface of revolution having anupright axis, means for supplying liquid to said surface to flowdownwardly thereover in a film under the influence of gravity, means forheating the liquid in said film to vaporize at least a part thereof, aframe mounted for rotary relative movement with respect to said surfaceof revolution about an axis that is within said surface, said framebeing formed with a plurality of condensing surfaces that extendgenerally axially of said surface of revolution and that arecharacterized by substantially uniformly shaped sections in transverseplanes and that are formed to return condensate that forms on acondensing surface to said surface of revolution by liquid iiow on saidcondensing surface, guide means mounted on said frame intermediate saidcondensing surfaces respectively, and an elongate wiper element mountedfor sliding, guided engagement of substantial radial extent with saidguide means for radial movement relative to said surface of revolutionthrough a radially-extending path at a constant orientation to saidsurface of revolution, constantly to present thereto one radially outerface, said element being mounted to e gage said surface of revolutionupon rotary relative movement between said frame and said surface ofrevolution and being formed at its said face with radially projectinglands and with recesses between said lands, said element and its saidlands and recesses having substantial angular extent relative to saidsurface of revolution thereby upon relative rotary movement between saidframe and said surface of revolution to engage said surface ofrevolution over broad bearing areas and to provide elongate chambersbetween said lands, whereby said wiper element can operate to removesaid iilm at the leading edges of said lands, pass the removed liquidinto said chambers to mix it therein, and discharge it from saidchambers respectively at a plurality of axially spaced locations on saidsurface of revolution again to form a film to flow downwardly under theinliuence of gravity.

2. Apparatus in accordance with claim l wherein said condensing surfacesare angularly spaced relative to each other and are characterized bysubstantially uniform curvilinear sections and are generally concave intransverse section relative to said surface of revolution.

3. Apparatus in accordance with claim l wherein said condensing surfacesare curved and are characterized by substantially uniformly curvilinearsections and are generally concave in transverse section relative tosaid surface of revolution in planes that are perpendicular to the axisof said surface of revolution at successive points along said axis, andare generated about axes that are equally radially-spaced respectivelyfrom the axis of said surface of revolution and that are equiangularlyspaced from each other.

4. Apparatus in accordance with claim l wherein said frame is mountedfor rotation relative to said surface of revolution and said wiperelement is mounted to engage said surface of revolution undercentrifugal force upon rotation of said frame. y

5. Apparatus for the distillation of liquid comprising a body having achamber that is formed with an internal surface of revolution having anupright axis, means for supplying liquid to said surface to flowdownwardly thereover in a film under the influence of gravity, means forheating the liquid in said film to vaporize at least a part thereof, aframe mounted within said chamber for rotary movement relative to saidsurface of revolution about an axis that is generally co-axial with theaxis of said surface of revolution, said frame being formed with aplurality of axially-extending angularly spaced curved condensingsurfaces that are characterized by substantially uniformly shapedsections and that are generally concave in planes that are perpendicularrelative to the axis Vof said surface of revolution at successive pointsalong said axis, and that have axially-extending radial extremities thatare disposed substantially uniformly closely adjacent said surface ofrevolution, and said condensing surfaces being formed to returncondensate that is formed on a condensing surface to said surface ofrevolution by liquid iiow over said condensing surface, a plurality ofchannel members mounted in generally axially-extending relation on saidframe between adjacent condensing surfaces respectively, with the openmouths of said channels confronting said surface of revolution, and acolumn of wiper elements mounted in each of said channels, each columncomprising a plurality of Wiper elements that are mounted one above theother and each of which has an axial length that is less than the axiallength of said surface of revolution, each of said wiper elements beingfree to move radially independently of said other elements, and havingaxially-extending side faces that are disposed in sliding engagementwith the side faces of the channel member in which it is mounted forpresentation of said wiper element to said surface of revolution at aconstant orientation, each said element being mounted to engage saidsurface of revolution upon rotary relative movement between said frameand said surface of revolution and being founed with radially outwardlyprojecting lands and with recesses between said lands, each element andits said lands and recesses having substantial angular extent therebyupon rotary relative movement between said frame and said surface ofrevolution to engage said surface of revolution over broad bearing areasand to provide elongate chambers between said lands, Whereby said wiperelements can operate to remove the film from said surface of revolutionat the leading edges of said lands, pass the removed liquid into saidchambers to mix it therein, and

discharge it from said chambers respectively at a plurality` of axiallyspaced locations on said surface of revolution again to form a film toflow downwardly under the iniiuence of gravity.

6. Apparatus in accordance with claim 5 wherein said frame is mountedfor rotation relative to said surface of revolution and said wiperelements are mounted for radial movement independently of each otherunder centrifugal force to engage said surface of revolution uponrotation of said frame.

7. Apparatus in accordance with claim 6 wherein said slots of said wiperelements are downwardly and rearwardly inclined relative to said surfaceof revolution and to the direction of movement of said framerespectively, to impart to the removed liquid in said elongate chambersa velocity having a component in an axially downward direction on saidsurface of revolution, thereby to accelerate movement of liquid axiallyover said surface of revolution.

8. Apparatus for the fractional distillation of liquid comprising a bodyhaving a chamber that includes a fractionating zone and a productrecovery zone, said fractionating zone including at least a part of saidchamber that is formed with an internal surface of revolution having anupright axis, means for supplying liquid to said surface to liowdownwardly thereover in a film under the influence of gravity, means forheating the liquid in said lm to vaporize at least a part thereof, aframe mounted in said fractionating zone for rotary movement relative tosaid surface .of revolution about an axis that is within said surface,said frame being formed -with a plurality of condensing surfaces forcondensing partially the vapor in s-aid fractionating zone, saidcondensing surfaces extending axially of said surface of revolution andbeing characterized by substantially uniformly shaped sections intransverse planes and that are disposed to return condensate that formson a condensing surface to said surface of revolution by liquid flow ofsaid condensate over said condensing surface, to provide for repeatedcondensation and vaporization in said fractionating zone, guide meansmounted on said frame intermediate said condensing surfacesrespectively, elongate Wiper elements mounted intermediate saidcondensing surfaces respectively for sliding, guided engagement ofsubstantial radial extent with said guide means for radial movementrelative to said surface of revolution at a constant orientation to saidsurface of revolution, constantly to present thereto one radially outerface, each of said elements being formed to engage said surface ofrevolution upon rotary relative movement between said frame and saidsurface of revolution and being formed at its said radially outer facewith radially projecting lands and with recesses 4between said lands,said element and its said lands and recesses having substantial fangular extent thereby upon rotary relative movement between said frameand said surface of revolution to engage said surface of revolution overbroad bearing areas and to provide elongate chambers between said lands,whereby said wiper elements can operate to remove said film at theleading edges of said lands, pass the removed liquid into said chambersto mix it therein, and discharge it from said chambers respectively at aplurality of axially spaced locations on said surface of revolution,again to form a film to flow downwardly under the influence of gravity,a second condenser disposed in said recovery zone and spaced from saidfirst condenser for condensing vapor from said fractionating zone, andmeans for recovering the condensate that is condensed on said secondcondenser.

9. Apparatus for the fractional distillation of liquid comprising a bodyhaving a chamber that includes a fractionating zone and a productrecovery zone, said fractionating zone including at least a part of saidchamber that is formed with an internal surface of revolution having anupright axis, means for supplying liquid to said surface to flowdownwardly thereover in a film under the infiuence of gravity, means forheating the liquid in said film to vaporize at least a part thereof, aframe mounted within said fractionating zone for rotary movementrelative to said surface of revolution about an axis that is generally 1co-axial with the axis of said surface of revolution, said frame beingformed with a plurality of condensing surfaces that extend generallyaxially of said surface of revolution and that are characterized bysubstantially uniformly shaped sections in transverse planes and toreturn con; densate that forms on a condensing surface to said surfaceof revolution by liquid flow over said condensing surface, channelmem-bers mounted on said frame intermediate said condensing surfacesrespectively to extend generally axially relative to said surface ofrevolution, said channel members being disposed with the open portionsof their channels respectively confronting said surface of revolution,columns of wiper blades mounted in said channel members respectively,each of said columns comprising a vertically arranged series ofsuperposed wiper blades each o-f which has an axial extent less than theaxial length of said surface of revolution, the blades in each columnhaving opposite sides engaging the sides of the associated channelmember in sliding relation over areas of substantial radial extent andbeing mounted for radial movement independently of each other to engagethat surface of revolution at a constant orientation upon relativerotary movement between said frame and said surface of revolution, eachof said blades being formed with radially projecting lands and withrecesses between said lands, said lands and said recesses havingsubstantial angular extent to engage said surface of revolution overbroad bearing areas and to provide elongate chambers between said lands,whereby said wiper blades can operate to remove said film at the leadingedges of said lands, pass the removed liquid into said chambers to mixit therein, and discharge it from said chambers respectively at aplurality of axially spaced locations on said surface of revolutionagain to form a film to fiow downwardly under the influence of gravity,a second condenser disposed in said recovery zone above said firstcondenser for condensing vapor from said fractionating zone, and meansfor recovering the condensate that is condensed on said secondcondenser.

l0. Apparatus in accordance with claim 9 in which said frame is'mountedfor rotation relative to said surface of revolution and said wiperblades are mounted to engage said surface of revolution undercentrifugal force upon rotation of said frame.

11. Apparatus in accordance with claim 9 wherein said condensingsurfaces vare curved and are characterized by substantially uniformlycurvilinear transverse sections that are generally concave relative tosaid surface of revolution in planes that are perpendicular to the axisof rotation of said frame at successive points along said axis and thatare generated about axes that are equally radially-spaced from said axisof rotation and that are equiangularly spaced from each other.

l2. A method for the fractional distillation of liquid comprisingapplying said liquid to at least a part of an internal surface ofdrevolution having an upright axis to flow downwardly thereover in afilm under the infiuence of gravity, heating the liquid in said film -tovaporize at least a part thereof, partially condensing the vapor,returning the condensate to said surface for reheating thereof,continuously positively mechanically engaging on said surface o-frevolution axially-spaced bearing areas that have substantial axialextent and that have an angular extent that is substantial but thatrepresents but a fraction of the angular extent of said surface ofrevolution, with the slotted faces of a column of independentlyradiallymovable wiping blades, rotating said column relative to saidsurface to remove the film from said surface at the leading edges ofsaid blades, continuously collecting the removed material in the slotsin said blade faces, continuously reapplying the removed material fromsaid slots onto said surface of revolution, again to fiow downwardlyover l said surface in film form, condensing the evolved vapor in anupperzone, and recovering as a product fraction `the vapor that iscondensed in said upper zone.

13. A method for the fractional distillation of liquid comprisingapplying said liquid to at least a part of a surface of revolutionhaving an upright axis to ow downwardly thereover in a film under theinfluence of gravity, heating liquid in said film to vaporize at lea-sta part thereof and to cause the vapor vto travel ifrom said film with acomponent in an upward direction relative to said surface of revolutionin a generally upward path between said surface of revolution and acurved condensing surface that extends axially of said surface ofrevolution and that is generally concave in transverse section relativeto said surface of revolution and that has axially extending radialextremities that are disposed closely adjacent said surface ofrevolution, partially condensing the vapor on said condensing surface,rotating said condensing surface about an axis that is generally coaxialwith the axis `of said surface of revolution to cause said condensingsurface to move relative to said surface of revolution therebycentrifugally to impel the condensate on said condensing surface to flowover said condensing surface to said surface of revolution, continuouslypositively mechanically engaging on said surface of revolutionaxially-spaced bearing areas that have substantial axial extent and thathave an angular extent that is substantial but that represents but afraction of the angular extent of said surface i i l l revolution, withthe faces of a column of rotary, independently radially-movable wipingblades, whose said faces are formed with slots that are uniformlydownwardly inclined relative to the surface of revolution and to thedirection of rotation thereof, rotating said column relative to saidsurface of revolution to remove the film from said surface of revolutionat the leading edges of said blades, continuously collecting the removedmaterial in the slots in said blade faces, continuously reapplying atleast a portion of the removed material from said slots onto saidsurface of revolution, againt to flow downwardly in iilm form,condensing the vapor in an upper Zone above said condensing surface, andrecovering as a product fraction the vapor that is condensed in saidupper zone.

14. Apparatus for the disillation of liquid comprising a body having awall that is formed to dene an internal surface of revolution, means forsupplying liquid to said surface to ow downwardly thereover in a tilmunder the influence of gravity, a heating jacket secured to the externalsurface of said wall to heat the liquid in said lrn to vaporize at leasta part thereof, a frame mounted for rotary relative movement withrespect to said surface of revolution about an axis that is generallycoaxial with the axis of said surface, said frame being formed with aplurality of condensing surfaces that extend generally axially of saidsurface of revolution and that are characterized by substantiallyuniformly shaped sections in transverse planes and that can functiontogether as a condenser to condense vapor evolved from said film and toreturn condensate that forms on a condensing surface to said surface ofrevolution by liquid ow over said condensing surface, means mounted onsaid frame intermediate said condensing surfaces respectively, anelongate wiper element mounted for sliding, guided engagement ofsubstantial radial extent with said guide means for radial movementrelative to said surface of revolution at a constant orientation to saidsurface of revolution, constantly to present thereto one radially outerface, said wiper element being formed to engage said surface ofrevolution upon relative rotary movement between said frame and saidsurface of revolution and being formed at its said face with radiallyprojecting lands and with recesses between said lands, said element andits said lands and recesses having substantial angular extent therebyupon relative rotary movement between said frame and said surface oirevolution to engage surface or' revolution over broad bearing areas andto provide enlongate chambers between said lands, whereby said Wiperelement can operate to remove said film at the leading edges of saidlands, pass the removed liquid into said chambers to mix it therein, anddischarge it from said chambers respectively at a plurality of axiallyspaced locations on said surface of revolution again to form a film toflow downwardly under the influence of gravity, and means connectingsaid heating jacket and said condenser in a closed thermal circuit forcirculating a heat exchange fluid therethrough to release heat in saidheating jacket and to absorb heat in said condenser.

References Cited in the le of this patent UNlTED STATES PATENTS2,306,265 Heald Dec. 22,1942 2,500,900 Madlen Mar. 14, 1950 2,546,381Zahrn Mar. 27, 1951 2,562,153 Taylor July 24, 1951 2,619,814 Kniel Dec.2, 1952 2,749,292 Perry et al June 5, 1956 2,766,193 Schneider Oct. 9,1956 2,848,388 Beuche Aug. 19, 1958 FOREIGN PATENTS 330,805 GreatBritain June 19, 1930 710,158 Great Britain June 9, 1954

12. A METHOD FOR THE FRACTIONAL DISTILLATION OF LIQUID COMPRISINGAPPLYING SAID LIQUID TO AT LEAST A PART OF AN INTERNAL SURFACE OFREVOLUTION HAVING AN UPRIGHT AXIS TO FLOW DOWNWARDLY THEREOVER IN A FILMUNDER THE INFLUENCE OF GRAVITY, HEATING THE LIQUID IN SAID FILM TOVAPORIZE AT LEAST A PART THEREOF, PARTIALLY CONDENSING THE VAPOR,RETURNING THE CONDENSATE TO SAID SURFACE FOR REHEATING THEREOF,CONTINUOUSLY POSITIVELY MECHANICALLY ENGAGING ON SAID SURFACE OFREVOLUTION AXIALLY-SPACED BEARING AREAS THAT HAVE SUBSTANTIAL AXIALEXTENT AND THAT HAVE AN ANGULAR EXTENT THAT IS SUBSTANTIAL BUT THATREPRESENTS BUT A FRACTION OF THE ANGULAR EXTENT OF SIAD SURFACE OFREVOLUTION, WITH THE SLOTTED FACES OF A COLUMN OF INDEPENDENTLYRADIALLYMOVABLE WIPING BLADES, ROTATING SAID COLUMN RELATIVE TO SAIDSURFACE TO REMOVE THE FILM FROM SAID SURFACE AT THE LEADING EDGES OFSAID BLADES, CONTINUOUSLY COLLECTING THE